This invention relates to hemostatic clips used to ligate or clamp blood vessels during surgical procedures and more particularly, to a cartridge for holding hemostatic clips. Even more particularly, the invention relates to a cartridge clip holder for securely retaining a plurality of preformed hemostatic clips prior to and during the withdrawal of the clips by a clip applicator.
Hemostatic clips have been used in surgery for over 60 years. They were designed to perform two basic functions--ligation of a vessel, nerve, or fluid duct in the human body; or marking a specific surgical site, typically the periphery of a tumor, which will later show up on x-ray. The clips are permanently implanted in the body and are radiopaque. Originally hemostatic clips were formed in a "V" shape. However, when this shape is closed, it tends to push the vessel away from the clip or cut the vessel rather than clamp it. This problem was solved by a preformed hemostatic clip which resembles the shape of a horseshoe, described in U.S. Pat. Nos. 3,323,216 and 3,363,628, which is now commonly used. The horseshoe clip has two essentially parallel legs which cause an initial distal tip to tip closing action that contains the vessel within the clip to fully control the vessel before ligation.
In a typical prior art cartridge for holding the clips, a plurality of clips is press fitted over a rigid plastic center post or pedestal. The outer contour of the pedestal matches the inner horseshoe-shaped contour of the clips, however, the clip is slightly smaller than the pedestal so contact tension between the parallel legs of the clip and the pedestal prevent the clips from falling out of the cartridge during shipping and when the cartridge is inverted or dropped. This contact tension causes several problems, however.
First, it causes the process of loading the clip into the jaws of an applicator to be very inconsistent. Although the jaws of the applicators are manufactured to very precise tolerances, there are thousands of applicators in use so the jaw width opening varies significantly. A very minor jaw width variation in the applicator will cause a significant variation in the action of transferring the preformed hemostatic clip from the cartridge to the applicator jaws. Applicators with a narrow jaw opening are very difficult to force over the clip, since the clip is already in very tight contact with the pedestal and therefore not able to compress. This causes significant friction between the applicator and clip and may cause metal to scrape away from the clip. When the applicator has wide jaws, the clip sometimes is not securely attached within the applicator jaws after being removed from the cartridge. This may cause the hemostatic clip to slip backward within the applicator jaws and away from the intended surgical site or fall out of the applicator.
A second problem caused by the contact tension is difficulty in removing the clip from the cartridge holder. Because the clip is in contact with the pedestal, significant friction exists between the pedestal and the clip, and the cartridge must be held in place to allow removal. Either the person applying the clip must hold the cartridge in one hand and the applicator in their other hand, or the cartridge must be weighted with a significant amount of weight, before the clip and applicator can be separated from the cartridge. This causes a significant inconvenience during a surgical procedure. Because the operating room nurse responsible for loading the clips has other duties, a free hand is often not available to grasp the cartridge. Adding a base weight to the cartridge is often ineffective, since the weight may be lifted off the work surface, and since the applicator can only be used in one position with a weight under the cartridge.
A third problem with the contact tension cartridges is that the clip may scrape material from the pedestal as it is being removed. The cartridge and pedestal are usually made of plastic, and the metal clip may scrape plastic off the pedestal as the clip and applicator are removed from the cartridge. This problem is more pronounced when the clip legs have projections on their occlusive surfaces, a desirable feature for the clips. The result is that the plastic that is scraped off sticks to the clip and is left in the wound of the patient.
Yet another problem exists with prior art clip cartridge holders. In order for the applicator to fit around and hold the clip, the jaws of the applicator must be thicker than the clip. Therefore, in order for the applicator to fit into the compartment containing the clip, the compartment must be wider than the clip. If the compartment is wider than the clip, the clip can be positioned several ways within the compartment and may not be centered in the compartment when the applicator is inserted, so the clip may not be transferred accurately to the center of the jaws of the applicator. A clip which is incorrectly seated into the jaws of an applicator will yield erratic clip closure results. In addition, if the applicator is subject to jarring, the clip may fall out of the applicator jaws into the wound.
Many others have attempted to solve these problems. U.S. Pat. No. 3,713,533 issued Jan. 30, 1973 to Reimels held "V" shaped clips in place by placing the legs of the clips under a lip of the cartridge rather than using contact tension with the pedestal. This cartridge was effective, but only for the "V" shaped clips--it will not work with the parallel legs of the preformed horseshoe-shaped clip.
In U.S. Pat. No. 4,076,120 issued Feb. 28, 1978 to Carroll, et al., the clip compartment is built with the same width as the clip, to keep the clip centered, and a space is cut in the walls of the compartments to allow the applicator to force the compartment walls apart as the applicator is being inserted into the compartment to pick up the clip. This requires significant force to insert and remove the applicator, since the walls would attempt to hold the applicator in the compartment slot, thus two hands or a weighted base would be required to use this device.
In U.S. Pat. No. 4,146,130 issued Mar. 27, 1979 to Samuels, et al., "V" shaped clips are held in place by the legs of the clips contacting the side walls of the cartridge. This device is somewhat similar to the Reimels device described above, however, in this device, the clip shape is changed from a "V" to a horseshoe by the pressure of the applicator as it is inserted over the clip. The pressure required to form the clip may cause the clip to embed itself into the pedestal and remove plastic as the clip is removed. If the clip embeds, it will be difficult to remove, thus two hands or a weighted base will be required. Also, the process of reforming the clip may scrape metal from the sides of the clip and deposit this metal near the end of the clip. The metal thus deposited may have sharp edges and be very loosely attached, so this sharp-edged metal may be dropped into the patient's wound.
The device of U.S. Pat. No. 4,294,355 issued Oct. 13, 1981 to Jewusiak, et al., is designed for plastic clips having a snap closure. In one embodiment, a transparent film covers the clips. This film is perforated or embossed to form a longitudinal line of weakness along the centerline of the clips, and to form crossing lines between each clip. As the applicator is inserted into a clip compartment, it ruptures the film so the clip can be removed. In other embodiments, the clip is held in place by springs mounted to the sides or bottom of the cartridge. In all embodiments of this device, the center rail has a step that is adapted specifically to hold a particular type of plastic hemostatic clip. Also, this device does not address the problem of centering the clips within the clip compartments. Because the film would be perforated before the applicator contacts the clip, the device might not be suitable for use in any position other than horizontal.
A film or tape covering for the clips is also present in U.S. Pat. No. 4,146,130, described above. A later patent, U.S. Pat. No. 4,696,396 by this same inventor, describes a problem with this tape. According to this second patent the tape described in the first patent may stick to the clip when the clip is being removed. Another problem with tape is that the tape obscures the compartments making it more difficult to detect an empty compartment.
The device of U.S. Pat. No. 4,361,229 issued Nov. 30, 1982 to Mericle is designed for a specific type of plastic hemostatic clip that has bosses on both sides of the clip legs. Fingers on the side of the cartridge engage the bosses until the applicator pushes them out of the way. Since the bosses are pushed entirely out of the way by the applicator before the applicator engages the clip, this device may not be suitable for use in any position other than horizontal. Also, in order to push the fingers out of the way, the clip is partially closed and must spring back into position after the fingers have passed by the bosses. This may cause a problem with the delicate hinge of plastic clips, and would not work with metal clips that have only a very small amount of springiness.
The device of U.S. Pat. No. 4,696,396 issued Sep. 29, 1987 to Samuels has protrusions, or channel members, extending into the clip compartment from the side walls of the compartment. These channel members hold the clip in place, however, they simply change the friction point from the pedestal to the side walls, so the clip is still held in place by friction with the cartridge. Thus all the problems associated with a friction fit still apply to this device. This device may also have problems with manufacturing tolerance since neither the clip nor the channel members can be adjusted as the clips are inserted into the cartridge, therefore neither a tight fit nor a loose fit can be accommodated.
It is thus apparent that there is a need in the art for an improved system for transporting and supplying preformed hemostatic clips. There is also a need in the art for such a system that allows a preformed clip to be inserted into an applicator using only one hand. There is another need for a system wherein the preformed clip does not bind on the cartridge as it is being removed. Another need is for a system that keeps the preformed clips centered within each clip compartment in a clip cartridge. Another need is for a system that allows the preformed clip to compress as the applicator is placed over the clip. Still another need is for a system that allows the cartridge to be positioned at any angle, with respect to horizontal, while retaining the preformed clips before and during removal.